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Summary: In 24 conscious newborn piglets the effects of 20 μg/kg body weight IV 1-deamino-8-d-arginine-vasopressin (DDAVP) in group 1,5 mg/kg PO indomethacin in group 2, and the combined effects of both drugs in group 3 were studied by measuring urinary flow rate, urinary osmolatity, creatinine clearance, total urinary and nephrogenous cyclic-adenosine 3':5'-monophosphate (cAMP) excretion, medullary cAMP content, and renal prostaglandin (PG)E2and PGF20, excretion. DDAVP alone had no significant effects on the above parameters, whereas indomethacin alone reduced only the PG excretion significantly. When both drugs were administered simultaneously, urinary concentration increased significantly (urinary flow rate decreased from 2.4 × 0.4 to 1.4 × 0.3 ml/hr (means × S.E.), and urinary osmolality increased from 444 × 29 to 552 × 33 mOsm/liter). Total urinary and nephrogenous cAMP excretion increased from 590 × 48 to 854 × 78 and 302 × 36 to 590 × 81 pmoles/hr/g kidney weight, respectively, whereas PGE2and PGF20decreased from 249 × 33 to 19 × 4 and 192 × 32 to 43 × 7 pg/hr/g kidney weight, respectively. In addition, medullary cAMP content was considerably higher in group 3 (2010 × 200 pmoles/g medulla) than that observed in the control (1187 × 137), DDAVP (1218 × 115), and indomethacin (1230 × 168) groups.Speculation: During the neonatal period, renal prostaglandins inhibit the antidiuretic hormone-dependent cyclic adenosine 3′:s′-monophosphate system.

The metabolites of prostacyclin and thromboxane A2, 6-ketoprostaglandin F1α and thromboxane B2, were measured in urine of 27 preterm and 21 full-term infants. Their values were analyzed in correlation to plasma renin activity, urinary function, and systolic blood pressure. The 6-ketoprostaglandin F1α excretion was significantly higher in the preterm infants as compared to the full-term infants (p < 0.001). This decrease of 6-ketoprostaglandin F1α in the full-term infants was associated with a decrease in the plasma renin activity and an increase in systolic blood pressure. In contrast, the urinary excretion of thromboxane B2 was low, without significant difference between the two groups, and there was no correlation to the parameters mentioned above.

In 24 conscious newborn piglets the effects of 20 μg/kg body weight IV 1-deamino-8-d-arginine-vasopressin (DDAVP) in group 1,5 mg/kg PO indomethacin in group 2, and the combined effects of both drugs in group 3 were studied by measuring urinary flow rate, urinary osmolatity, creatinine clearance, total urinary and nephrogenous cyclic-adenosine 3':5'-monophosphate (cAMP) excretion, medullary cAMP content, and renal prostaglandin (PG)E2and PGF20, excretion. DDAVP alone had no significant effects on the above parameters, whereas indomethacin alone reduced only the PG excretion significantly. When both drugs were administered simultaneously, urinary concentration increased significantly (urinary flow rate decreased from 2.4 × 0.4 to 1.4 × 0.3 ml/hr (means × S.E.), and urinary osmolality increased from 444 × 29 to 552 × 33 mOsm/liter). Total urinary and nephrogenous cAMP excretion increased from 590 × 48 to 854 × 78 and 302 × 36 to 590 × 81 pmoles/hr/g kidney weight, respectively, whereas PGE2and PGF20decreased from 249 × 33 to 19 × 4 and 192 × 32 to 43 × 7 pg/hr/g kidney weight, respectively. In addition, medullary cAMP content was considerably higher in group 3 (2010 × 200 pmoles/g medulla) than that observed in the control (1187 × 137), DDAVP (1218 × 115), and indomethacin (1230 × 168) groups.